Download Document

Joints intro
A joint is the point where two or more
bones meet. There are three main types:
Fibrous (immoveable),

Cartilagenous (partially moveable)
and

Synovial (freely moveable) joint.

THE JOINTS
SYNOVIAL JOINT
Cavities between bones in
synovial joints are filled with
synovial fluid. This fluid helps
lubricate and protect the
bones. Bursa sacks contain
the synovial fluid.
The bursitis is the
inflammation of the bursa.
Characteristics of synovial joints
1. Articular cartilage: This is a smooth, white, shiny mass that covers
the articular surfaces of bone. It protects bone tissue and reduces friction
(rubbing) between bones when they move.
 2. Articular capsule: The articular capsule attaches to the bones near
the edge of their articulating surfaces. The capsule is made of strong
fibrous tissue and surrounds the joint, adding stability and stopping
unwanted material from entering and irritating the joint. The capsule also
provides a cavity for synovial fluid to work within.
 3. Synovial fluid: yellowish oily fluid that lubricates the articulating
surfaces, forms a fluid cushion between surfaces, provides nutrient for
cartilage and absorbs debris that is produced by friction between
articulating surfaces.
4. Ligaments: These are strong fibrous bands that join articular
surfaces, controlling movement and providing stability.
5. Articular discs (meniscus): Some synovial joints such as the knee
have menisci. These are made of tough fibrous tissue and their function
is to absorb shock and maintain joint stability. They lie between the
articulating surfaces and as such protect the surfaces of articulating
bone, as seen in the previous image.
6. Bursae: These are found in some synovial joints. They are closed
sacs filled with synovial fluid. Their role is to reduce friction that can
occur with movement, such as when tendons rub over bones.

Types of SYNOVIAL JOINT

pivot joint
Enables rotation around a lengthwise axis: the
cylindrical terminal part of a bone is encased in a
hollow cylinder. Examples include the tibia and
the fibula.

ball-and-socket joint
Allows movement along three axes, such as in
the shoulder: flexion and extension, rotation, and
adduction (arm drawing near the trunk) and
abduction (arm drawing away from the trunk).

hinge joint
Enables flexion and extension along a single axis.
The elbow is a particularly good example: the
round terminal part of the humerus turns in the
hollow of the ulna.



condyloid joint
An example is the wrist, which the hand can
move on two axes: flexion and extension; it can
also be tilted sideways (toward the radius and
ulna).
saddle joint
Resembles the condyloid joint but allows a wider
range of motion; this type of joint is rare.
gliding joint
Surfaces of these joints are relatively flat and not
very mobile; they allow only a narrow gliding
range (e.g., vertebrae, certain bones of the
carpus).
Shoulder Joint
Dr. Nabil Khouri 2015
ARTICULATION
Articulation is between:
• The rounded head of the
humerus and
• The shallow, pear-shaped
glenoid cavity of the scapula.
10
• The articular surfaces are covered
by hyaline cartilage.
• The glenoid cavity is deepened by
the presence of a
fibrocartilaginous rim called the
glenoid labrum.
11
Joint Type
• Synovial
• Ball-and-socket joint
12
Synovial Membrane
• It lines the fibrous capsule.
• It is attached to the margins of the cartilage
covering the articular surfaces.
• It forms a tubular sheath around the tendon of the
long head of the biceps brachii.
• It extends through the anterior wall of the capsule
to form the subscapularis bursa beneath the
subscapularis muscle.
SYNOVIAL MEMBRANE
16
FIBROUS CAPSULE
• The fibrous capsule surrounds the joint and is attached:
Medially to the margin of the glenoid cavity outside the labrum;
Laterally to the anatomic neck of the humerus.
18
• The capsule is thin and lax, allowing a wide range of movement.
Ligaments of the shoulder joint
Ligamnets of the shoulder
1. The glino humeral legaments: are three weak
bands of fibrous tissue that strengthen the
front of the capsule.
2. The transverse humeral ligament strengthens
the capsule and bridges the gap between the
two humeral tuberosities.
3. Coraco humeral ligament : strengthens the
capsule from above and stretches from the
root of the coracoid process to the greater
tuberosity of the humerus.
Accessory ligaments:
• The coracoacromial ligament extends
between the coracoid process and the
acromion. Its function is to protect the
superior aspect of the joint.
LIGAMENTS
21
Shoulder (Anterior View)
•
•
•
•
The long head of the biceps brachii originates from the supraglenoid tubercle of
the scapula,
It is intracapsular but extrasynovial
It's tendon passes through the shoulder joint and emerges beneath the
transverse humeral ligament.
Inside the joint, the tendon is surrounded by a separate tubular sheath of the
synovial capsule.
Movements
• Flexion
• Extension
• Abduction
• Adduction
• Lateral
rotation
• Medial
rotation
Flexion
• Normal flexion is about
90°
• It is performed by the:
1.
2.
3.
4.
Anterior fibers of the deltoid
Pectoralis major
Biceps brachii
Coracobrachialis
Extension:
• Normal extension is
about 45°
• It is performed by the:
1. Posterior fibers of the deltoid,
2. Latissimus dorsi
3. Teres major
Abduction:
• Abduction of the upper limb
occurs both at the shoulder
joint and between the scapula
and the thoracic wall.
• It is initiated by supraspinatus
from 0 to 18
• Then from 19 to 120 by the
middle fibers of the deltoid.
• Then above 90 by rotation of
the scapula by 2 muscles the
Trapezius & Seratos Ant.
Adduction:
• Normally the upper limb
can be swung 45° across
the front of the chest.
• This is performed by:
1.
2.
3.
4.
pectoralis major
latissimus dorsi
teres major
teres minor
Lateral rotation:
• Normal lateral rotation is about 40
to 45°.
• This is performed by the:
1. infraspinatus
2. teres minor
3. the posterior fibers of the
deltoid muscle
Medial rotation:
• Normal medial rotation is about
55°.
• This is performed by the:
1. subscapularis
2. latissimus dorsi
3. teres major
4. anterior fibers of the deltoid.
Stability of Joint
• This joint is unstable because of the:
– shallowness of the glenoid fossa
– weak ligaments
• Its strength almost entirely depends on the tone of the rotator cuff muscles.
• The tendons of these muscles are fused to the underlying capsule of the
shoulder joint.
• The least supported part of the joint lies in the inferior location, where it is
28
unprotected
by muscles.
Wrist drop
•
•
•
A subglenoid displacement of the head of the humerus into the quadrangular space can
cause damage to the axillary nerve.
This is indicated by paralysis of the deltoid muscle and loss of skin sensation over the
lower half of the deltoid.
Downward displacement of the humerus can also stretch and damage the radial nerve.
29
ELBOW Joint
Synovial Hinge Joint
Articulation
 Trochlea and
capitulum of
the humerus
above

Trochlear
notch of ulna
and the head
of
radius
below
ELBOW Joint
 The articular
surfaces
are
covered with
articular
(hyaline)
cartilage.
Capsule
Anteriorly: attached
 Above
 To the humerus along
the upper margins of
the coronoid and radial
fossae and to the front
of the medial and lateral
epicondyles.
 Below
 To the margin of the
coronoid process of the
ulna and to the anular
ligament,
which
surrounds the head of
the radius.
Capsule
Posteriorly: attached
 Above
 To the margins of
the olecranon fossa of
the humerus.
 Below
 To the upper margin
and sides of the
olecranon process of
the ulna and to the
anular ligament.
Ligaments
Lateral (Radial Collateral) Ligament
 Triangular in shape:
 Apex
 Attached to the
lateral epicondyle
of humerus
 Base
 Attached to the
upper margin of
annular ligament.
Ligaments
Medial (Ulnar Collateral)
Ligament
 Anterior strong cord-like
band:
 Between
medial
epicondyle and the
coronoid process of
ulna
 Posterior weaker fan-like
band:
 Between
medial
epicondyle and the
olecranon process of
ulna
 Transverse band:
 Passes between the
anterior
and
posterior bands
Synovial Membrane
 This
lines
the
capsule and covers
fatty pads in the
floors
of
the
coronoid, radial, and
olecranon fossae.
 Is continuous below
with
synovial
membrane of the
superior radio-ulnar
joint
Relations
Anterior:
Brachialis
Tendon of Biceps
Median nerve
Brachial artery
Posterior:
Triceps muscle
Small bursa intervening
Lateral:
Common extensor
tendon
The supinator
Medial:
Ulnar nerve
Bursae around the elbow
joint:
 Subcutaneous
olecranon
bursa
 Subtendinous
olecranon
bursa
Movements
Flexion
Is limited by the anterior
surfaces of the forearm and
arm coming into contact.
Extension
Is limited by the tension of
the anterior ligament and the
brachialis muscle.
The joint is supplied by branches
from the:
Median
Ulnar
Musculocutaneous
Radial nerves
Carrying Angle
 Angle
 Between the long axis of the
extended forearm and the long axis of
the arm
 Opens
 Laterally
 About
 170 degrees in male and 167
degrees in females
 Disappears
 When the elbow joint is flexed
1650-1700
Articulations
 The elbow joint is stable because of the:
 Wrench-shaped articular surface of
the olecranon and the pulley-shaped
trochlea of the humerus
 Strong medial and lateral ligaments.
 Elbow dislocations are common & most
are posterior.
 Posterior dislocation usually follows
falling on the outstretched hand.
 Posterior dislocations of the joint are
common in children because the parts
of the bones that stabilize the joint are
incompletely developed.
ELBOW Joint
 Avulsion of the epiphysis of the
medial epicondyle is also common
in childhood
CUBITAL FOSSA
Cubital fossa showing boundaries
44
• The roof of the cubital fossa is formed by superficial
fascia and skin.
• The most important structure within the roof is the
median cubital vein, which passes diagonally across
the roof and connects the cephalic vein on the lateral
side of the upper limb with the basilic vein on the
medial side.
• The bicipital aponeurosis separates the median cubital
vein from the brachial artery and median nerve.
• Other structures within the roof are cutaneous nervesthe medial cutaneous and lateral cutaneous nerves of
the forearm.
47
4/29/2017
Superficially, in the
subcutaneous tissue
overlying the fossa
median cubital vein,
medial and lateral
antebrachial cutaneous
nerves
basilic and cephalic
veins.
48
CONTENTS OF CUBITAL FOSSA
The major contents of
the cubital fossa,
from lateral to
medial, are:
• The tendon of the
biceps brachii
muscle;
• The terminal part of
brachial artery;
• The median nerve.
50
1) Terminal part of the
brachial artery,radial and
ulnar arteries
2) Biceps brachii tendon
3) Median nerve
4) Radial nerve
5) (Deep) accompanying
veins of the arteries
Position of the
radial nerve
• The median nerve
lies immediately
medial to the
brachial artery
and leaves the
fossa by passing
between the ulnar
and humeral
heads of the
pronator teres
muscle.
• The brachial artery and the median nerve are covered
and protected anteriorly in the distal part of the
cubital fossa by the bicipital aponeurosis.
• This flat connective tissue membrane passes between
the medial side of the tendon of the biceps brachii
muscle and deep fascia of the forearm.
• The sharp medial margin of the bicipital aponeurosis
can often be felt.
median nerve lies
immediately medial to the
brachial artery and leaves
the fossa by passing
between the ulnar and
humeral heads of the
pronator teres muscle.
radial nerve lies under
brachioradialis
(lateral margin of the fossa)
gives off deep branch of the
radial nerve and continues
as superficial radial nerve.
• The brachial artery normally bifurcates
into the radial and ulnar arteries in the
apex of the fossa, although this
bifurcation may occur much higher in the
arm, even in the axilla.
• When taking a blood pressure reading
from a patient, the clinician places the
stethoscope over the brachial artery in
the cubital fossa.